Separation and recovery of RE and Mn from MN rare earth mud in China

A study was carried out to recover RE and Mn from the rare earth mud of wes tern Sichuang in China, which contains about 3-7% RE and 2-10% Mn. The RE o f the mud exists in amorphous Mn-Fe oxide. It is necessary to destroy the M n-Fe amorphous structure to recover the RE from the mud. A 3.6-g/l Na2SO4 s olution was first used to leach Mn at room temperature. About 90% Mn was le ached and the Mn-Fe amorphous structure was destroyed. The leaching solutio n is further treated with KMnO4 to remove impurities. A MnCO3 product with purity of 90.5% can be obtained. At the same time, the removed Mn mud is fu rther roasted with NH4Cl at about 450 degrees C, and then directly leached by water. The recovery of RE can reach to 73.4%, which is higher about 20% than that of the mud being directly roasted. The purified leaching solution is precipitated by NH4HCO3 and an easy filtered crystal RE2(CO3)(3) is obt ained. Based on the study, a flow sheet of separation and recovery of RE an d Mn from MN rare earth mud was proposed. (C) 2000 Published by Elsevier Sc ience B.V. All rights reserved.